Peg tooth harrow



United States Patent PEG TOOTH HARROW Knud Sorensen, Rock Island, and Emil F. Ohlendorf, Molme, Ill., assignors, by mesne assignments, to Deere & Company, a corporation of Delaware Application January 3, 1955, Serial No. 479,445

4 Claims. (Cl. 172-621) The present invention relates generally to peg tooth harrows and more particularly to harrows having independently movable tooth bars.

The object and general nature of the present invention is the provision of a peg tooth harrow wherein each tooth bar may rock rearwardly, as when the teeth thereon encounter an obstruction, with new and improved means for yieldably opposing such independent rocking movement. A further feature of this invention is the provision of spring arms connected between the tooth bars and an adjusting and interconnecting link member, the spring arms being constructed and arranged so that when a tooth bar rocks to permit the teeth thereon to swing rearwardly, as when overloads are encountered, the spring arms are not subjected to concentrated stresses, whereby spring failures are substantially entirely eliminated.

A further feature of this invention is the provision of a spring arm construction for connecting the tooth bars of a peg tooth harrow with an associated adjusting and anchoring link member, the spring arms being so constructed and arranged that the spring arms do not buckle when yielding under overload conditions, but instead are arranged with curved portions that, during the yielding of the spring arms, are moved toward straightened position with the result that, during the rocking of the tooth bars in the frame members of the harrow, the spring arms are, in effect, connected with the tooth bars at progressively changing points of contact, whereby concentration of stresses at a single point of connection is avoided. Still further, according to the present invention, the spring arms are connected to the associated tooth bars so that when the latter yield to permit the associated teeth to swing rearwardly, the spring arms are, in effect, wrapped around the tooth bars so that in this way concentration of stresses is avoided.

A further feature of this invention is a spring arm and tooth bar arrangement such that the arm is fixed to the bar without using weakening holes in the arm, as for rivets or the like, and the spring arm is not required to bend or flex relative to the bar at a single point adjacent a rivet hole or the like.

These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description of the preferred structural embodiment, taken in conjunction with the accompanying drawings in which that embodiment is illustrated.

In the drawings:

Fig. l is a side view of a peg tooth harrow in which the principles of the present invention have been incorporated.

Fig. 2 is an enlarged sectional view taken generally along the line 2-2 of Fig. 1.

Fig. 3 is an end view of the parts shown in Fig. 2.

The harrow shown in Fig. 1 comprises a frame that includes two side bars 5 and 6 arranged generally in parallel relation and apertured along their lengths to receive the rounded ends 7 of the associated tooth bars 2,930,438 Patented Mar. 29, 1960 8. The frame also includes a front crossbar 9 and suitable connections 11 whereby forward draft may be applied to the harrow to drag it over the field being worked. Each tooth bar 8 carries a plurality of teeth 13, and the angle that the latter make with respect to the ground surface may be adjusted by a hand lever and sector arrangement indicated generally diagrammatically in Fig. 1 by the reference numeral 15, which arrangement also includes a fore-and-aft extending link member 16 lying above and transversely with respect to the tooth bars 8. A harrow of this general construction is shown in US. Patent 2,236,780, issued April 1, 1941 to German, to which reference may be made if desired.

The present invention is concerned primarily with the provision of new and improved spring arms that are connected between the generally central portion of each tooth bar 8 and the adjusting link member 16. Referring now to Figs. 2 and 3, it will be seen that the link member 16 is provided with a plurality of openings 17 in each of which a connecting pin 18 is disposed. Each pin is arranged so that an end thereof extends laterally outwardly at opposite sides of the link member 16. Preferably, as best shown in Fig. 2, each pin 18 is provided at one end with a head 21 and at the other end with an aperture in which a cotter pin 22 is arranged.

Each tooth bar 8 is connected by a pair of spring arms 25 to the link member 16, and each spring arm 25 preferably is of tapered construction, as indicated at 26, having at one end an eye 27 that rockably receives the associated end of the pin 18. The other end of each spring arm 25 is formed with a right angle bend, as indicated at 28, whereby the lower end 29 of each spring fits substantially fiat against the front side of the associated tooth bar 8 while the adjacent portion 31 lies against the forward part of the upper face of the tooth bar 8. The lower portions 29 of each spring arm 25 are held in fixed relation against the tooth bar 8 by means of a clamping cap 33 and an associated U-bolt 34 that encircles the tooth bar 8 and has a threaded end extending through apertures in the cap 33 to receive nuts 35 that, when tightened, clamp the spring arms to the tooth bar ,8. The U-bolt 34, as will be seen from Fig. 2, is disposed in the space S between the tooth bars 25 of each pair, the associated adjusting link member 16 being disposed in the upper portion of the space S.

In operation, when one or more teeth of one of the tooth bars 8 strike an obstruction or the like, the associated spring arm 25 connecting that tooth bar with the connecting link member 16 permits the tooth bar 8 to pivot and the teeth 13 to swing rearwardly. As the tooth bar 8 pivots in the frame 5, 6, as will be seen from Fig. 3, the lower portions of the arms 25 are, in effect, wrapped around the tooth bar 8 with the result that the rearwardly curved portion 26 approaches its straightened position and, in addition, the point of bending contact between the lower part of each arm 25 and the tooth bar 8 shifts from one position, as at a to b. Thus, there is no concentration or stresses in the arms 25 when the tooth bar 8 pivots. The upper ends of the arm 25 pivot on the pin 18.

Since the spring arms 25 are curved, as shown in Fig. 3, no slots in the arms are necessary to receive the pins 18. Instead, the eyes 27 provide substantially continuous cylindrical contact with the pin ends. This reduces wear at these points.

While we have shown and described above the preferred structure in which the principles of the present invention have been incorporated, it is to be understood that the present invention is not to be limited to the particular details, shown and described above, but that, in fact, widely different means may be employed in the practice of the broader aspects of our invention.

What we claim, therefore, and desire to secure by Letters Patent is:

1. In a peg tooth harrow, frame means including a pair of side bars, a plurality of tooth bars pivoted at their ends on said side bars, each of said tooth bars being polygonal in cross section, harrow teeth fixed to said tooth bars and adapted to work the soil when drawn in one direction, and adjusting means connecting said tooth bars and including a link member extending across said tooth bars, a plurality of pins carried by said link member in transverse relation, one pin for each tooth bar, and an end of each pin extending outwardly at each side of said link member, a pair of spring arms connecting each tooth bar with said link member, each spring arm having an eye formed at its upper end and rockably receiving the adjacent end of the associated pin, each spring arm having a substantially right angle bend at its lower end adapted to engage two adjacent sides of the associated tooth bar and curved tangentially from one of said two sides toward the point of connection of the spring arm with the link member, and means fixing each pair of spring arms to the associated tooth bar in laterally spaced apart relation so as to receive said link member therebetween, said means comprising a bracket clamping the lower end of each arm to the forward side of the tooth bar and fastening means lying between the associated spring arms and clamping said bracket to the tooth bar.

2. The invention set forth in claim 1, further characterized by each of said spring arms tapering toward its upper end.

3. In a peg tooth harrow, frame means including a pair of side bars, a plurality of tooth bars pivoted at their ends on said side bars, harrow teeth fixed to said tooth bars and adapted to work the soil when drawn in one direction, each of said tooth bars being non-circular in section and having two substantially fiat sides adjacent one another, one at the front of the tooth bar and the other at the upper portion thereof, adjusting means connecting said tooth bars and including a link member extending across said tooth bars, a spring arm connecting each tooth bar with said link member, each spring arm having a substantially right angle bend at its lower end portion arranged so that the lower end lies against the front side of the associated tooth bar and the adjacent portion lies partially against the upper side of the tooth bar and is curved tangentially away from said upper side and extends rearwardly and upwardly toward the point of connection of the spring arm with the link member, the associated harrow teeth extending downwardly, means pivotally connecting the upper end of each spring arm to said link member, and means fixing each spring arm to the front side of the associated tooth bar, said front side of each tooth bar swinging generally downwardly and rearwardly when one or more teeth thereon encounter a substantially unyielding obstruction, such movement of the tooth bar moving said spring substantially into a straight line position, whereby the spring arm, thus straightened, serves to define a limit to the premissive rocking of the associated tooth bar.

4. In a peg tooth harrow normally drawn in a forward direction, frame means including a pair of side bars, a plurality of tooth bars pivoted at their ends on said bars, each of said tooth bars being polygonal in cross section, harrow teeth fixed to and extending generally downwardly from said tooth bars and adapted to work the soil when drawn in a forward direction, and adjusting means connecting said tooth bars and including a link member extending across said tooth bars, each tooth bar having a substantially transverse generally upwardly facing fiat side positioned so as to move at least partially downwardly away from said link member when the associated teeth move backwardly as under an overload, a spring arm connecting each tooth bar with said link member, each spring arm being disposed generally in upright position and having a lower end portion and an upper end portion, each spring arm normally being curved rearwardly and upwardly between its end portions, means fixing the lower end portion of each spring arm to the associated tooth bar so that the curved portion adjacent its lower part lies against the forward portion of said upwardly facing fiat side of the associated tooth bar end extends upwardly and rearwardly from the rear portion of said fiat side, means connecting the upper end portion of each spring arm to the associated link member, whereby as the harrow teeth on a tooth bar swing rearwardly under an overload, the normally curved spring arm is moved toward a straightened position and during the initial portions of said swinging, additional portions of the spring arm are progressively brought against said fiat side of said associated tooth bar.

References Cited in the file of this patent UNITED STATES PATENTS 239.043 Gray Mar. 22, 1881 274,684 Wells Mar. 27, 1883 311,544 Thomas Feb. 3, 1885 448,446 Mackey Mar. 17, 1891 974,427 Powers Nov. 1, 1910 1,907,946 Furrer May 9, 1933 2,568,572 Van Zee Sept. 18, 1951 2,610,456 Strandlund Sept. 16, 1952 

